if you include the total with the parts in a pie chart why will the percentage for the Doro always be 50%

The pie chart is actually a very clever visual design that conveys one fact above all others with a minimum of visual cues: that the circle (the “pie”) represents some kind of whole, which is made up of the slices. Add up all the slices and you get the complete pie. Take out one slice, and the whole will be missing exactly this part. Enlarge one part, and other parts will need to shrink.

What this means is that the pie chart first and foremost represents the size relationship between the parts and the entire thing. If a company has five divisions, and the pie chart shows profits per division, the sum of all the slices/divisions is the total profits of the company.

If the parts do not sum up to a meaningful whole, they cannot be represented in a pie chart, period. It makes no sense to show five different occupations in a pie chart, because there are obviously many missing. The total of such a subsample is not meaningful, and neither is the comparison of each individual value to the artificial whole.